This invention relates to a zoom lens system for a digital camera, video camera or the like, particularly to a compact and axially-thin zoom lens system of, for example, a power variation ratio of 3 and a field angle of 60° or more at a wide-angle end which is fit for CCD (charge coupled device) and CMOS (complementary metal-oxide semiconductor).
Recently, there have been lots of digital still cameras and video camera which use CCDs or CMOSs. Particularly, only thin cameras have enjoyed an increasing demand. A three-element cemented lens system whose axial length is suppressed has been disclosed for such thin cameras. (See Patent Document 1.)
[Patent Document 1] Japanese Non-Examined Patent Publication 2004-325975
The second lens group of the zoom lens system of Patent Document 1 is composed of a positive single lens and a three-element cemented lens system which contains a negative lens, a positive lens, and a negative lens in this order when viewed from the object side. When the second lens group is configured in this manner, the lateral magnification of the three-element cemented lens system cannot avoid from becoming bigger. Therefore, as the lens errors of the lens thickness occur, the paraxial values such as focal lengths and back-focus and aberration changes will be greater. This is a problem.